The present invention relates to power devices for fastening various construction materials and more particularly to devices which automatically control the spacing between consecutive fasteners such as nails, staples and screws.
The construction industry has many requirements for fastening one material to another using nails, staples or screws. Power fasteners manufactured by companies such as SENCO (Senco is the trademark of Senco Products, Inc., Cincinnati, Ohio USA), HITACHI (Hitachi is the trademark of Hitachi, Ltd., Tokyo, Japan)and BOSTICH (Bostich is the trademark of The Stanley Works, New Britain, Conn. USA) are used to drive various fasteners through one material and into another to hold the two materials in a fixed position with respect to one another. The fastening of roof sheeting to the trusses of a house using nails or staples is one example. The distance or spacing between adjacent fasteners is the xe2x80x9cschedulexe2x80x9d for specific fastening applications. This schedule may be defined by a code such as the Uniform Building Code or by the specification of the contractor. The schedule for a given application is very critical since the schedule affects the structural integrity of the joined materials.
The power fasteners currently available leave the spacing or distance between adjacent fasteners (the xe2x80x9cschedulexe2x80x9d) to the trained eye of the operator. The operator operates a trigger mechanism to drive the fastener into the materials after he or she has navigated the power fastener to the proper location. A safety mechanism prevents the power fastener from driving a fastener when the unit is not properly positioned relative to the surface of the construction material, or pre loaded. Other than seeing that the safety interlock is operated by placing the nose of the power fastener on the surface and depressing the interlock, an operator determines fastener location by pulling the trigger of the power fastener when the perceived proper location is achieved. It is obvious that where an operator is forced to judge the distance between adjacent fasteners, a great deal of variation can occur in the schedule for the same application. If the operator chooses a reduced spacing, a great deal of time and material may be wasted. If the operator errs by choosing an increased spacing, the structural integrity may be compromised.
Thus, as will appear, the present invention fulfills a long time need for a simple device which attaches to a power fastener and which automatically produces an equal spacing between the fasteners being driven as the power fastener is moved along the surface of the material being fastened. The present invention also fulfills a need for such a device which is incorporated into the power fastener itself.
The present invention, an automatic fastener scheduler, disclosed herein is a device which, as will appear hereafter in a greater detail, attaches to a power fastener such as a HITACHI power nailer and automatically operates the fastener when the scheduler has moved a fixed distance from the last fastener installed. The distance or spacing between adjacent fasteners (the xe2x80x9cschedulexe2x80x9d) is set in advance by the operator for a given application according to the specification for the application. Once the schedule has been set, the operator merely pulls the trigger and rolls the device along the path of the fasteners. The device automatically cycles the power fastener to drive fasteners according to the schedule set by the operator. The device can easily attach to a variety of power fasteners, therefore allowing the device to schedule nails, staples or screws depending upon the power fastener to which it is attached. The device can be fitted with a handle and remote trigger so that the operator can walk behind the device in an upright stance much like the operator of a walk-along lawn mower. The safety interlock feature of the power fastener is maintained and uninterrupted.
The invention also lends itself to being incorporated as a part of the power driving mechanism and safety features of a power fastener to operate as a complete xe2x80x9cstand alonexe2x80x9d device to automatically drive fasteners according to a set schedule.
The present invention, as will appear, is a rolling base equipped with provisions for the attachment of a standard power fastener for driving fastening products such as nails, staples or screws. The attachment arrangement of the power fastener to the present invention provides for ease of attachment and removal of the power fastener. Further, the power fastener, when removed from the invention, can be utilized independent without the automatic spacing feature while leaving the attachment clamps of the present invention still mounted to the power fastener. The wheels of the base allow an operator to roll the invention along lines where fastening products are required to be driven for the joining of two materials. A cam is rotationally and fixedly attached to at least one of such wheels in such a way that as the base is rolled, a cam follower causes the power fastener to be pivoted up and down. Because of the way in which the power fastener is attached to the rolling base, this up and down pivoting action operates the safety interlock of the-power fastener each time the power fastener is in a preselected position, i.e., the down position, and the safety interlock is in contact with the material to be joined. If the operator depresses the trigger of the power fastener at the time the safety interlock is opened by the operation of the cam and cam follower, a fastener is driven. The invention essentially xe2x80x9cbumpsxe2x80x9d the power faster against the material at each location a fastener is required. The dimensions of the lobes of the cam are chosen to produce a travel or pivoting action sufficiently great to open the safety interlock each time the power fastener is xe2x80x9cbumpedxe2x80x9d against the material. The spacing between adjacent fasteners along the line of attachment is determined by the circumference of the wheel or wheels which drive the cam and the number of lobes on the cam. Therefore, the fastener schedule can be adjusted to a required specification by installing drive wheels of the proper diameter. For example, a cam with two equally spaced lobes will drive two equally spaced fasteners for each rotation of the wheel. Therefore, a fastener spacing of 6xe2x80x3 would require a drive wheel having a diameter of somewhat less than 4xe2x80x3. The spacing between adjacent fasteners can also be adjusted by driving the cam at a different rotational speed than that of the wheel through the use of gearing or a pulley and timing belt system. For example, the above-described system of a two lobed cam and 4xe2x80x3 diameter drive wheel could be caused to produce a fastener spacing of 12xe2x80x3 by including a 2:1 reduction gearing arrangement between the drive wheel and the cam.
Although this description of present invention has focused on the application of the invention within the construction industry it is clear that the invention has application to any field in which a power device is used to join two or more materials with fasteners such as nails, staples or screws where such fasteners are required to be placed at fixed intervals, i.e. with a fastening schedule.
Accordingly, it is a primary object of the invention to provide a simple device which provides for the easy attachment and removal of a variety of power fasteners to automatically space adjacent fasteners according to a predetermined schedule as the invention is rolled along a path.
It is a further object of the invention to provide a simple device which can be incorporated into a complete xe2x80x9cstand alonexe2x80x9d power fastener which can automatically drive fasteners according to a predetermined fastening schedule.
These and further objects, as shall hereafter appear, are readily fulfilled by the present invention in a remarkably unexpected manner as will be readily discerned from the following detailed description of an exemplary embodiment thereof especially when read in conjunction with the accompanying drawings in which like parts bear like numerals throughout.